The field of invention relates generally to micro-fabrication of structures. More particularly, the present invention is directed to methods and the imprinting materials to form layers having uniform etch characteristics.
Micro-fabrication involves the fabrication of very small structures, e.g., having features on the order of micro-meters or smaller. One area in which micro-fabrication has had a sizeable impact is in the processing of integrated circuits. As the semiconductor processing industry continues to strive for larger production yields while increasing the circuits per unit area formed on a substrate, micro-fabrication becomes increasingly important. Micro-fabrication provides greater process control while allowing increased reduction of the minimum feature dimension of the structures formed. Other areas of development in which micro-fabrication has been employed include biotechnology, optical technology, mechanical systems and the like.
An exemplary micro-fabrication technique is shown in U. S. Pat. No. 6,334,960 to Willson et al. Willson et al. disclose a method of forming a relief image in a structure. The method includes providing a substrate having a transfer layer. The transfer layer is covered with a polymerizable fluid composition. An imprint device makes mechanical contact with the polymerizable fluid. The imprint device includes a relief structure formed from lands and grooves. The polymerizable fluid composition fills the relief structure, with the thickness of the polymerizable fluid in superimposition with the lands defining a residual thickness. The polymerizable fluid composition is then subjected to conditions to solidify and polymerize the same, forming a solidified polymeric layer on the transfer layer that contains a relief structure complimentary to that of the imprint device. The imprint device is then separated from the solidified polymeric layer such that a replica of the relief structure in the imprint device is formed in the solidified polymeric layer. The transfer layer and the solidified polymeric layer are subjected to an environment to selectively etch the transfer layer relative to the solidified polymeric layer such that a relief image is formed in the transfer layer. Thereafter, conventional etching processes may be employed to transfer the pattern of the relief structure into the substrate.
Conventional etching processes form desired patterns in a layer employing an appropriate mask, e.g., a photoresist mask. The mask is typically deposited on the layer and patterned, forming a patterned mask. The patterned mask is then exposed to an etchant, such as ions in a dry etch process or a liquid acid in a wet etch technique, to remove portions of the layer exposed through the patterned mask.
A desired characteristic of any etch process is to obtain a uniform etch rate over the surface being etched. To that end, the prior art is replete with attempts to control the etch rate during an etching process. For example, U. S. Pat. No. 6,132,632 to Haney, et al., discloses a method and apparatus for achieving etch rate uniformity in a reactive ion etcher. The reactive ion etcher generates a plasma within a vacuum chamber for etching a substrate disposed at a cathode of a reactor can within the chamber wherein the plasma emanates from a top plate of the reactor can, and is influenced by localized magnetic fields for locally controlling etch rates across the cathode to produce a uniform etch rate distribution-across the cathode as a result of the localized magnetic field. The magnet array may be disposed between the top plate and the vacuum chamber for providing the localized magnetic fields. The magnet array includes a plurality of individual magnets and a grid plate for holding the individual magnets in position.
U.S. Pat. No. 6,344,105 to Daugherty et al. discloses a method and apparatus for ion-assisted etch processing in a plasma processing system. In accordance with various aspects of the invention, an elevated edge ring, a grooved edge ring, and a RF coupled edge ring are disclosed. The invention operates to improve etch rate uniformity across a substrate (wafer). Etch rate uniformity improvement provided by the invention not only improves fabrication yields but also is cost efficient and does not risk particulate and/or heavy metal contamination.
U.S. Pat. No. 6,576,408 to Meador et al. discloses anti-reflective coating compositions having improved etch rates. The compositions are prepared from certain acrylic polymers and copolymers, such as, glycidyl methacrylate reacted with non-polycyclic carboxylic acid dyes and non-polycyclic phenolic dyes, all light absorbing at a wavelength of 193 nm.
There is a need, therefore, to provide etching techniques with improved control of the etch rate of the imprinting material undergoing processing.